Looking for my father?

I would love to be able to find my father. His name is Stephen Anderson, I was born in 1977 and his family lived in Aspley in Brisbane, Qld. Unfortunately my mother had a severe mental illness and I was orphaned at 9. My mother Dianne Lynch and Stephen once lived together around 1976 at The Grange in Brisbane, Qld. I have no siblings and have had 3 children that I would love for them to know there Great Grandparents. I have been searching for him for the past 14 years with no luck.